Factory fabricated fireplace construction

ABSTRACT

Presented is a fireplace construction all major components of which are factory fabricated and merely assembled at the job site. The fireplace construction incorporates apparatus for adjusting the height of the hearth dependent upon conditions at the site such as grade, height, and level.

United States Patent [191 Tidwell 1March 20, 1973 [54] FACTORY FABRICATED FIREPLAC CONSTRUCTION [76] Inventor: Joe Dean Tidwell, 3404 Polaris Street, Modesto, Calif. 93 350 [22] Filed: Dec. 6, 1971 [21] Appl. No.: 204,927

[52] US. Cl ..'...126/l20, 52/219 [51] Int. Cl ..F24b 1/18 [58] Field of Search ..l26/l20; 52/122, 126', 219

' [56] References Cited UNITED STATES PATENTS 2,752,691 7/1956 Bender ..l26/l20X 3,460,525 8/ 1969 Bryant ..l26/120 3,466,000 9/1969 Southern et al. ....l26/l20 X 3,538,656 11/1970 Anger ..52/519 Primary Exam iner-Meyer Perlin Assistant Examiner-Ronald C. Capossela Attorney-John J L'eavitt ABSTRACT Presented is a fireplace construction all major components of which are factory fabricated and merely assembled at the job site. The fireplace construction incorporates apparatus for adjusting the height of the hearth dependent upon conditions at the site such as grade, height, and level.

' 1-1 Clainis, 10 Drawing Figures PATENTEnu'ARzo 1975 saw 1 [IF 4 INVENTOR.

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JOE D. TIDWELL PATENTEUHAmma 3 7 1, 25

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JOE D. TIDWELL FACTORY FABRICATEI) FIREPLACE CONSTRUCTION BACKGROUND OF THE INVENTION With the increase in wages and salaries, the construction industry, like every other major industry, has had to look toward ways in which the cost of construction can be reduced. This has been necessary because the increased cost of materials and labor has made the cost of residences prohibitive, resulting in difficulty of prospective purchasers of residences qualifying for financial assistance. One of the methods by which costs are reduced, is to factory fabricate as much of a residence as is economically feasible and then haul the factory-fabricated components of the residence to the job site and there erect them. In this regard, it has been found that if factory fabrication can be followed for all those components of the residence that are primarily functional in nature as opposed to esthetic, great savings can be effected. One of these areas includes fireplace construction, which'is highly functional in the residence environment, but in general contributesvery little from an esthetic point of view.

It is of course well known that fireplaces have heretofore been factory fabricated. One of the problems however that has occurred with previous conventional prefabricated fireplaces has been the difficulty with e which such prefabricated units, generally massive and monolithic and of greatweight, are hauled to the job site and erected in proper position. In most such instances, it has been necessary for a construction con-- tractor to employ the services of highly paid crane and rigging crews to load the massive and monolithic prefabricated fireplaces onto appropriate transport equipment, and then utilize the same crane and rigging crews to offload the fireplaces and stand them in proper position at the job site. The need for utilizing such massive equipment and specialized help to a large extent eliminates the savings attributable to mass production of the fireplace, thus defeating the basic purpose for factory fabricating the fireplaces. Accordingly, it is one of the principal objects of the present invention to provide a fireplace construction in which all major components of the fireplace are prefabricated or factory fabricated, but in which the major portions are sufficiently light that they may be handled in the usual way by construction workers already on the site and erected individually in an efficient manner.

Another disadvantage frequently found with prefabricated conventional fireplaces is that all of the fireplaces look the same. It is of course understandable that this would be the case since in a mass produced production method it is difficult and expensive to. introduce modifications in the basic structure directed merely to a change in the esthetics of the fireplace. Accordingly, it is a still further object of the invention to produce a factory fabricated fireplace structure capable of being erected on the building site and having the versatility of permitting adaptations to suit the esthetic desires of the purchaser of the residence.

Another difficulty 1 frequently found with prefabricated fireplaces constructed by assembly line techniques is that variations in the grade and level at the job site in relation to the floor chosen for installation by the owner of the residence creates problems related to the height of the hearth of the fireplace in relation to the finished floor. Accordingly, another object of the present invention is to provide a factory fabricated fireplace construction in which the height of the hearth may be adjusted over a wide range to accommodate the fireplace to the specific needs of an individual residence.

Fireplaces are ordinarily considered as a permanent part of a residence' In areas subject to earthquakes, fireplaces constructed on the job site are reinforced with iron embedded directly into the fireplace walls. In otherareas, however, where earthquakes do not occur, the inclusion of such reinforcing members is superfluous, increasing the cost and weight of the resulting structure. Conventional prefabricated fireplaces must of course be fabricated to meet the most stringent conditions, namely the types of stresses that might be imposed in an area subject to earthquakes. This being the case, it will 'be apparent that such conventional prefabricated fireplaces are more costly than is necessary when installed in areas not subjected to earthquake stresses. Accordingly, it is another object of the present invention to provide a factory fabricated fireplace construction in which the component parts are arranged'and installed at the job site with only whatever amount of reinforcing iron is required for the specific locality in which the fireplace is being' erected.

The invention possesses other objects and features of advantage, some of which, with the. foregoing, will be apparent from thefollowing description and the drawings. It is to be understood, however, that the invention is not limited to the embodiment illustrated and described, as it may be embodied in various forms within the scope of the appended claims.

BRIEF SUMMARY OF INVENTION In terms of broad inclusion, the factory fabricated fireplace construction of the invention comprises a hearth adjustment apparatus adapted to be supported on a prepoured concrete fireplace pad or footing. The hearth adjustment apparatus is operative to control the height of the hearth in relation to the finished floor of the residence in which the fireplace is installed. The hearth adjustment apparatus also functions to support a factory fabricated firebox superimposed on the hearth adjustment apparatus so as to position the floor of the firebox appropriately in relation to the finished floor of the residence. Superimposed over the firebox, and including damper means thereon, is a flue liner fabricated in a multiplicity of sections so that successive sections of the flue liner may be superimposed one above the other during erection of the fireplace. Means constituting exterior wall sections for the fireplace when completed are provided, fabricated in sections of such size that they may be easily manipulated by one or two men without any special crane or rigging apparatus, or at most, a light truck mounted hoist. The exterior wall sections are proportioned in relation to the hearth adjustment apparatus and firebox, and segmented flue liner, so as to provide a hollow space between the exterior wall portions and these inner parts which may be progressively filled with concrete as the fireplace is assembled at the job site.

3 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view, portions of the structure being broken away to reduce its height. In the interest of clarity of illustration, portions of the structure are illustrated in elevation.

FIG. 2 is-an enlarged cross-sectional view. illustrating the interengagement between adjacent portions of the outside shell of the fireplace.

FIG. 3 .is a perspective view in elevation of the completed fireplace.

FIG. 4 is an enlarged front elevation, portions of the structure being broken away to reveal the underlying construction.

FIG. 5 is a horizontal cross-sectional view taken in the plane indicated by the line 5--5 in FIG. 4.

FIG. 6 is a horizontal cross-sectional view taken in the plane indicated by the line 66 in FIG. 4.

FIG. 7 is an enlarged fragmentary perspective view illustrating the method of assembly of the major component parts of the factory fabricated fireplace construction.

. FIG. 8 is a view similar to FIG. 7, in perspective, portions of the structure being broken away, and illustrating the method of assembly of an upper portion of the fireplace construction.

.FIG. 9 is a perspective view showing the relationship between various parts of the fireplace construction.

FIG. 10 is a perspective view, partly in vertical section, illustrating the relationship of various parts of the factory fabricated fireplace construction.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, there is there shown in cross-section and elevation the major components utilized to assemble the factory fabricated fireplace at the job site. As there shown, the site on which the factory fabricated fireplace is to be assembled is provided with a fireplace pad or footing 2, preferably constituting a slab of poured concrete extending above the site grade a small amount and including an elevated portion 3 and a relatively lower portion 4. As indicated in dash lines, vertically extending reinforcing rods 6 are provided anchored at their lower ends in the concrete footing and spaced to project upwardly into the fireplace construction for purposes of reinforcing the fireplace structure after it is assembled As shown in FIG. 1, the forward elevated portion 3 of the footing stands at a somewhat higher elevation than the relatively lower portion 4, the difference in height being defined by the vertical wall portion 7. Resting on the relatively lower portion 4 of the footing is an exterior fireplace wall section designated generally by the numeral 8 and including a rear wall 9 integral with forwardly extending side walls 12 and 13 extending generally perpendicular to the rear wall 9 and terminating in forward-wall sections 14 and 16, respectively. It should be noted that the forward wall sections 14 and 16 are provided with lateral mutually opposing edges that are spaced apart to provide an opening 17 for the lowermost exterior wall section 8 for purposes which will hereinafter be explained in greater detail. It should be noted that the upper edges of rear, side and front walls 9-16 are provided with a V-shaped groove 18 adapted to receive a complementary V-shaped rib-19 depending from the lower-edge 21 of the next succeeding superposed exterior wall section designated generally by the numeral 22. This construction is shown in FIG. 2.

Seated within the exterior wall section 8 of the fireplace is a hearth adjustment apparatus designated generally by the numeral 26. The hearthadjustment apparatus is generally [-shaped to conform to the configuration of the enclosing exterior fireplace section 8, and is provided with a rear wall 27 lying spaced from and; parallel to the rear wall 9 of the exterior wall section 8. The hearth adjustment apparatus is also provided with forwardly extending side walls 28 and 29, lying spaced from and parallel to side walls 12 and 13, respectively,

of the surrounding exterior wall section 8.

As illustrated in FIG. 7, each of the forwardly extending side walls 28 and 29 is provided with a forward edge 31 abutting the interior surface of wall sections 14 and 16 as shown. Thus, the inner surfaces of the forwardly extending side walls 28 and 29 of the hearth ad-. justment apparatus define sides for the opening 17 formed in the surrounding exterior wall section 8. It

should also be noted that the spacing between the ex-- ten'or wall section 8 and the interiorly disposed hearth adjustment apparatus is such as to permit the reinforcing rods 6 anchored in the footing toextend up through such space. It should also be noted that the exterior surfaces 32 of wall portions 14 and 16 of the exterior wall section closely abut the vertically extending wall surface 7 defined between the-footing portions 3 and 4. This construction is illustrated in FIGS. 1,5, 6 and 7.

To provide a measure of adjustment for the hearth to be assembled in the fireplace, the rear wall 27 of the hearth adjustment apparatus is provided with a plurality of longitudinally extending grooves 36, adjacent grooves defining between them a horizontal ledge 37 having a supporting surface. 38 thereon adapted to receive and support the rearwardly'projecting complementarily configured edge 39 of a factory fabricated concrete slab 41, the bottom surface 42 of which coninterposed between the top surface 44 of the foundahorizontal attitude by equalizing the height of the triangular hearth adjustment bar and-the height of the associated support surface 38 of the rear wall 27.

It should be noted that the hearth adjustment bar is factory fabricated as illustrated in FIG. 10, with longitudinally extending grooves 46 constituting weakened sections in the hearth adjustment bar to permit breaking off of oneor more sections of the bar extending down from the apex thereof so as to modify the height of the adjustment bar and thereby effectively support the hearth support slab 41 at different heights. The break lines or grooves 46 formed in the hearth adjustment bar are correlated to the elevation of each of the support surfaces 38 above the top surface 47 of the fireplace footing so that a single hearth may be utilized to accommodate different hearth heights.

It will be of course understood that when the range of adjustment is so great as to be incapable of satisfaction by a single hearth adjustment bar of a predetermined size, additional hearth adjustment bars of different sizes and different spacings between the grooves 46 may be utilized. Additionally, the hearth adjustment bar may be configured so that its bases have an elevation or height which coincides to the elevation of one of the support surfaces 38 when the hypotenuseof the hearth adjustment bar is laid flat on the surface 44 of the fireplace footing.

Once the exterior fireplace wall section 8 and hearth adjustment apparatus as previously discussed have been properly positioned, as illustrated in FIGS. 1 and 7, concrete is poured into the space 5.1 defined between the exterior fireplace wall section 8 and the interior hearth adjustment apparatus 26 so as to retain the two sections in assembled position. In this respect, it is noted that the upper edges of the exterior fireplace wall section 8 and the hearth adjustment apparatus coincide in height so that the space may be substantially completely filled with concrete. In this respect, it is noted that the space beneath the forwardly projecting edge of the hearth support slab 41, between the hearth adjustment bar 43 and a framing member 52 may also be filled with concrete 53 to as to further support the forward edge of the hearth support slab 41.

The next step in the assembly 'of the factory fabricated fireplace construction is to support on the hearth support slab 41 the factory fabricated fire box designated generally by the numeral 56. The firebox is preferably fabricated from appropriate fire brick, and includes a floor 57 supported directly on the hearth support slab 41 and including the steel door 58 appropriately disposed over an ash drop aperture 59 extending downwardly through the floor 57 and the hearth support slab 41 so as to permit the deposition of ashes into the ash pit 61 disposed below the hearth support slab 41 in a space between the hearth adjustment bar 43, wall 7, and rear wall 27 of the hearth adjustment apparatus. Access to the ash pit is had through an exterior access door 62 and a passageway 63 formed through the exterior fireplace wall section 8 and the wall 27 of the hearth adjustment apparatus.

The fire box 56 also includes rearwardly converging side walls 64 and 66, the rear edges of which are joined by a rear wall 67 as shown in FIG. 4, 6 and 9. Rear wall 67 is vertical for a portion of its height and then inclines forwardly toward the top edge 68 of the fire box unit as illustrated in FIG. 1. After the fire box is appropriately positioned with respect to the left and right sides of the fireplace construction, and also with respect to the depth of the fireplace, concrete 69 is poured into the void defined between the interior of the fireplace wall section 22 and the back and sides of the fire box to retain it in position. In this respect, it will be noted that such concrete forms a continuation of the concrete poured into the void defined between the lower exterior fireplace wall section 8 and the hearth adjustment apparatus 27 previously discussed. It will thus be seen that as the fireplace construction is assembled, the

component parts are bound together by concrete so as to ultimately form a monolithic structure.

After placement of the fire box as described above, the base unit of a flue liner is superimposed over the upper end of the fire box unit 56 as illustrated in FIGS.

1, 4, 5 and 9. The base unit of the flue liner is preferably fabricated in a single piece from appropriate clay material baked as is usual with such flue liners. The flue base unit is designated generally by the numeral 71 and is positioned in association with the upper end of the fire box so as to be the first flue unit to receive smoke from the upper open end of the fire box. The flue base unit is provided with a horizontal transversely extending panel portion 72 constituting a smoke shelf, the forward edge 73 of which fits snugly up against the back surface of the back wall 67 of the fire box at a point below the top edge 68 thereof.

The smoke shelf 72 is joined integrally along its rear edge remote from edge 73 by a vertically extending back wall 74 lying parallel to the associated surrounding fireplace wall section 76. The base flue unit is also provided with side walls 77, and 78 which at their lower edge portions are vertical as illustrated at 79 in FIG. 4, and which at the'level of top edge 68 of the fire box converge inwardly to merge smoothly with vertically extending 'side wall sections 81 and 82 respectively.

The base flue unit is also provided with a front wall 83, the lower edge 34 of which lies flush with the top edge 68 of the fire box'as illustrated in FIGS. 1, 4 and 9. From its lower forward edge 84, the front wall 83 recedes backwardly, joining the side walls 77 and 78 and merging with a vertically extending front wall portion 86, the latter cooperating with side wall portions 81 and. 82 and rear wall 74 to form a generally rectangular or square flue liner transition portion.

As indicated in FIG. 1, the top edge 68 of rear wall 67 of the fire box is spaced rearwardly from the front edge 84 of the base flue unit so as to define an opening or throat 87 through which smoke and products of combustion can pass from the fire box 56 into the base flue unit 71. The opening or throat 87 is controlled by a damper assembly designated generally by the numeral 88 and including a downwardly depending handle 89 and a baffle plate 91 pivotally mounted as at 92 on opposing side walls 77 and 78 of the base flue unit. Manipulation of the handle 89 will effect either closing or opening of the throat 87 to permit products of combustion to rise up from the fire box to the throat 87 and into the base flue 71.

After placement of the base flue unit, the opening 93 between the lateral edges of the front wall portions of the surrounding exterior fireplace wall section 76 are blocked by a baffle plate designated generally by the numeral 94 and including a cross piece 96 connecting oppositely disposed and downwardly depending leg portions 97 on opposite sides of the base flue unit so as to block the opening 93 on each side thereof. Once this baffle plate is in position, concrete is poured into the void defined between the exterior wall section 76 and the base flue unit so as to retain the base flue unit in its proper position with respect to the underlying fire box.

To extend the height of the prefabricated fireplace, and forming a transition between the exterior wall section 76 and succeeding superimposed outside wall sections 101, 102, 103, and 104, there is provided the posed sections 101-104.

transition unit designated generally by the numeral 106. This transition unit is illustrated in FIG. 3 and as there shown constitutes a cap having laterally extending portions 107 and 108 fitting snugly over the wall section 76. The transition unit is proportioned to span the distance between the side walls of the outside fireplace wall section 76 and is provided with an interlocking rib and groove as illustrated in FIG. 2 so as to form an air-tight union. For purposes of shedding water that might fall on the laterally extending portions 107 and 108, these sections taper rearwardly to provide inclined surfaces from which water may run off. The transition section also includes a generally rectangular 'or square section 109 integral with the laterally extending sections 107 and 108, but smaller in its dimensions, being proportioned to lie in alignment with the super- As indicated in FIG. 8, the reinforcing iron 6 is bent inwardly as illustrated in the vicinity of the transition section so as to follow the countour of the sides of the baseflue unit, with extensions 6' extending upwardly within the space defined between the interior of sections 103-104 and the exterior of upwardly projecting sections of flue liner 112 illustrated in dash lines in FIG.

It will of course be understood that prior to application of the transition member 106, all of the voids surrounding the base flue liner unit are packed with concrete so that the position of the base flue liner will be stabilized in relation to the underlying fire box. After placement of the transition unit, concrete is poured into the space surrounding the structural iron so as to bind the entire structure together in a monolithic unit. Thereafter, outside fireplace wall sections 101-104 are successively placed in superposed relationship and sealed in proper position to whatever height is desired. It should be understood that the interior flueliner 112 illustrated in FIG. 9 is also fabricated in sections and these sections are positioned within the exterior fireplace sections 101-104 as the assemblycontinues, concrete being poured between the coaxially aligned units. When the fireplace has been assembled to the desired height, the entire structure is capped by placement of a factory fabricated cap structure 116 illustrated in FIG. 3. As there shown, the cap structure comprises laterally extending skirt portions 1 17, proportioned to overlap the exterior surface of the uppermost outside wall section 104 by a slight amount to provide a drip cap. Centrally disposed in the cap 116 is an aperture through which the upper end .of one of r the flue liner sections 1 12 extends for a short portion as illustrated at 118.

It'will thus be seen that upon completion of assembly of the fireplace, the structure will be strong and rigid and monolithic, have the slight imperfections and characteristics that indicate the fireplace is the result of hand craftsmanship which most homeowners like to see, thus making the product more saleable, while at the same time permitting mass production of components by assembly line techniques to cut down the cost of manufacture. Once assembled, the interior of the fireplace wall may be lined with decorative brick or field stone as indicated at 119 in FIG. 1, to provide any desired esthetic effect that the homeowner may wish to incorporate.

Having thus described my invention, what is claimed to be novel and sought to be protected by letters patent, is as follows:

I claim:

1. In a factory fabricated fireplace including a hearth in combination with a pre-poured concrete footing:

a. a hearth adjustment apparatus seated on the concrete footing to control the height of the fireplace hearth;

. a fire box assembly mounted on said hearth adjustment apparatus;

. a base flue liner unit superimposed over said fire 'box assembly, the interior of said base flue liner unit communicating with the interior of said fire box to permit the passage of products of combustion therebetween;

. flue liner means superimposed over said base flue liner unit and communicating the interior of said base flue liner unit with the ambient atmosphere; v and factory fabricated exterior fireplace wall means surrounding said hearth adjustment apparatus, said fire box, said base flue liner unit and said flue liner means, to provide a space therebetween adapted to be filled by concrete to retain the fireplace components in a rigid composite whole.

2. Thecombination according to claim 1, in which said hearth adjustment apparatus includes a factory fabricated generally [-shaped unit including a rear wall having a multiplicity of vertically spaced hearth support surfaces;

3. The combination according to claim 1 in which said hearthadjustment apparatus includes a vertical wall section having a multiplicity of horizontally extending hearth support surfaces thereon at graduated elevations above the surface of said foundation footing, and a hearth adjustment bar having a height adjustable to coincide with the height of a selected one of said hearth support surfaces on said wall section, said fire box assembly being supported in a level attitude by one of said selected hearth support surfaces and said hearth adjustment bar.

4. The combination according to claim 1, in which said fire box assembly includes a floor, side walls and a rear wall factory fabricated from fire brick to form a rigid component, said fire box assembly being supported on said hearth adjustment apparatus.

5. The combination according to claim 1, in which said base flue liner unit and said fire 'box assembly cooperate to form a passageway therebetween constituting a throat through which products of combustion may pass.

6. The combination according to claim I, in which said base flue liner unit includes a smoke shelf disposed behind and abutting said fire box assembly below the point of communication of the interior of said fire box assembly with the interior of said base flue liner unit.

7. The combination according to claim I, in which a passageway defining a throat communicates the interior of said fire box assembly with the interior of said base flue liner unit, and a damper assembly is disposed in said throat manipulable to open or close said communicating passageway.

8. The combination according to claim 1, in which said factory fabricated exterior fireplace wall means includes a transition member disposed between said exterior fireplace wall means surrounding said base flue liner unit and said exterior fireplace wall means surrounding said flue liner means superimposed over said base flue liner unit.

9. The combination according to claim 1, in which a cap member is provided surroundingthe upper edge portion of the flue liner means and superposed over the exterior fireplace wall means. 7

I 10. The combination according to claim 1, in which arranged end-to-end coaxially within said exterior fireplace wall means. 

1. In a factory fabricated fireplace including a hearth in combination with a pre-poured concrete footing: a. a hearth adjustment apparatus seated on the concrete footing to control the height of the fireplace hearth; b. a fire box assembly mounted on said hearth adjustment apparatus; c. a base flue liner unit superimposed over said fire box assembly, the interior of said base flue liner unit communicating with the interior of said fire box to permit the passage of products of combustion therebetween; d. flue liner means superimposed over said base flue liner unit and communicating the interior of said base flue liner unit with the ambient atmosphere; and e. factory fabricated exterior fireplace wall means surrounding said hearth adjustment apparatus, said fire box, said base flue liner unit and said flue liner means, to provide a space therebetween adapted to be filled by concrete to retain the fireplace components in a rigid composite whole.
 2. The combination according to claim 1, in which said hearth adjustment apparatus includes a factory fabricated generally (-shaped unit including a rear wall having a multiplicity of vertically spaced hearth support surfaces.
 3. The combination according to claim 1 in which said hearth adjustment apparatus includes a vertical wall section having a multiplicity of horizontally extending hearth support surfaces thereon at graduated elevations above the surface of said foundation footing, and a hearth adjustment bar having a height adjustable to coincide with the height of a selected one of said hearth support surfaces on said wall section, said fire box assembly being supported in a level attitude by one of said selected hearth support surfaces and said hearth adjustment bar.
 4. The combination according to claim 1, in which said fire box assembly includes a floor, side walls and a rear wall factory fabricated from fire brick to form a rigid component, said fire box assembly being supported on said hearth adjustment apparatus.
 5. The combination according to claim 1, in which said base flue liner unit and said fire box assembly cooperate to form a passageway therebetween constituting a throat through which products of combustion may pass.
 6. The combination according to claim 1, in which said base flue liner unit includes a smoke shelf disposed behind and abutting said fire box assembly below the point of communication of the interior of said fire box assembly with the interior of said base flue liner unit.
 7. The combination according to claim 1, in which a passageway defining a throat communicates the interior of said fire box assembly with the interior of said base flue liner unit, and a damper assembly is disposed in said throat manipulable to open or close said communicating passageway.
 8. The combination according to claim 1, in which said factory fabricated exterior fireplace wall means includes a transition member disposed between said exterior fireplace wall means surrounding said base flue liner unit and said exterior fireplace wall means surrounding said flue liner means superimposed over said base flue liner unit.
 9. The combination according to claim 1, in which a cap member is provided surrounding the upper edge portion of the flue liner means and superposed over the exterior fireplace wall means.
 10. The combination according to claim 1, in which said factory fabricated exterior fireplace wall means comprises a multiplicitY of separate sections adapted to be superimposed one above the other in sealing engagement.
 11. The combination according to claim 1, in which said flue liner means superimposed over said base flue liner unit comprises a multiplicity of flue liner sections arranged end-to-end coaxially within said exterior fireplace wall means. 